The present invention relates to a side printing method and an apparatus therefor for photographically exposing or entering identifying marks comprising characters, numerals, symbols, signs or the like or combinations thereof as a latent image on an unexposed filmstrip for motion pictures and still pictures and, more particularly, to a method and an apparatus which is suitable for photographically exposing a series of different marks comprising characters, numerals, symbols, signs, or combinations thereof on an unexposed filmstrip along its longitudinal margin.
In film manufacturing, identifying marks such as the name of the manufactuere, the date the film was manufactured, the type of film or other identifying data are photographically exposed onto an unexposed filmstrip as a latent image at positions between a series of perforations and a longitudinal edge of the filmstrip. The identifying mark exposing, which is generally known as side printing, appears as, in one case, a common mark on a longitudinal margin of a filmstrip at regular intervals and, in another case, different or consecutive numerals such as footage numbers on, for instance, a motion picture filmstrip at regular intervals.
In such side printing, conventionally, it has been usual to use a rotary printing drum for photographically exposing the identifying marks onto a filmstrip. The rotary printing drum includes a light source, for instance a lamp, therewithin and has a window which is formed at a certain position in the periphery thereof and which is provided with a film plate with a negative image of the mark to be photographically exposed onto the filmstrip. As the filmstrip is continuously advanced around the peripheral surface of the rotary drum, the image of the mark on the film plate is illuminated by the light source and thereby projected on the filmstrip, so that the mark is photographed onto the filmstrip. In the case that different marks are photographed onto a filmstrip at regular intervals, the rotary printing drum further includes, therein, a mark counter comprising a cylinder member with a plurality of windows each having a film plate with a negative image of the mark to be photographically exposed and surrounding a light source. With the advance of a filmstrip, the mark counter rotates so that different marks are projected in sequence on a filmstrip through an aperture formed in a cylindrical light shielding cover surrounding the mark counter and a window of the rotary printing drum and thereby photographed onto a margin of the filmstrip.
There has been proposed a different type of a side printing apparatus, as described in Japanese Utility Model Publication No. 56-16589, which comprises a mark plate with various marks recorded thereon, a plurality of lens systems forming images of the respective marks on a filmstrip and a plurality of LEDs for illuminating the respective marks. In the side printing apparatus, the LEDs are selectively activated to emit light according to the advanced length of a filmstrip which is detected by using a rotary encoder rotating simultaneously with the film advance and a counter for counting pulses from the rotary encoder so as to project a mark to be photographically exposed onto the filmstrip.
Mainly because of the construction having a mark plate or plates, for instance a negative film plate, with specified marks in both apparatus just mentioned, exposing various special marks requires another mark plate to be displaced, resulting in a cumbersome procedure. Furthermore, the provision of various kinds of mark plates entails difficultly in controlling the mark plates. And in conventional apparatus having no detecting means of a damaged light source, there is a greater possibility to be unsuccessful in printing marks on a filmstrip owing to a damaged light source.